Overcoming degradation in spatial multiplexing systems with stochastic nonlinear impairments

Single-mode optical fibres now underpin telecommunication systems and have allowed continuous increases in traffic volume and bandwidth demand whilst simultaneously reducing cost- and energy-per-bit over the last 40 years. However, it is now recognised that such systems are rapidly approaching the limits imposed by the nonlinear Kerr effect. To address this, recent research has been carried out into mitigating Kerr nonlinearities to increase the nonlinear threshold and into spatial multiplexing to offer additional spatial pathways. However, given the complexity associated with nonlinear transmission in spatial multiplexed systems subject to random inter-spatial-path nonlinearities it is widely believed that these technologies are mutually exclusive. By investigating the linear and nonlinear crosstalk in few-mode fibres based optical communications, we numerically demonstrate, for the first time, that even in the presence of significant random mixing of signals, substantial performance benefits are possible. To achieve this, the impact of linear mixing on the Kerr nonlinearities should be taken into account using different compensation strategies for different linear mixing regimes. For the optical communication systems studied, we demonstrate that the performance may be more than doubled with the appropriate selection of compensation method for fibre characteristics which match those presented in the literature

Lateral Approach to the Popliteal Artery for Free Tissue Transfer to the Lower Extremity.

Free tissue transfer to the proximal leg and knee requires appropriate recipient vessel selection. The popliteal vessels have historically been unpopular choices, due to their remote location often necessitating vein grafts, and need for prone positioning. In this report, we describe a lateral approach to the above-knee popliteal vessels, which was utilized for 2 cases of free tissue transfer to the lower extremity. Neither prone positioning nor vein grafts were needed. The lateral approach to the above-knee popliteal vessels and their branches is a viable option for the otherwise recipient vessel-depleted lower extremity

Salmonella osteomyelitis of the hand in an infant with sickle cell disease.

Salmonella osteomyelitis involving the hand is a rare, but potentially morbid, complication of sickle cell disease in children. This entity can be difficult to distinguish from the more frequent presentation of dactylitis, but accurate diagnosis is critical to direct proper treatment. We report on a 15-month-old patient with sickle cell disease who ultimately developed osteomyelitis of 1 hand after an acute vasoocclusive episode caused 4 extremity dactylitis. The case description illustrates the diagnostic and treatment challenges

Frequency of Elevations in Markers of Cardiomyocyte Damage in Otherwise Healthy Newborns

Myocardial damage in infancy is a risk factor for eventual cardiac disease. Given that myocardial stress is greatest during the perinatal period and that the neonatal period is when the majority of pediatric heart failure occurs, we sought to determine whether even otherwise healthy neonates might have sub-clinical myocardial damage, and if so, what characteristics might identify them. We assayed umbilical cord and neonatal serum samples from 32 normal neonates for biomarkers of myocardial injury. No neonate had clinical evidence of cardiac or other abnormalities. Serum cardiac troponin T (cTnT) was elevated in 19 of 25 (76%) cords and in 16 of 17 (94%) neonates; levels indicating myocardial infarction (≥0.2 ng/mL) were found in 2 patients (1 umbilical cord and 1 neonatal sample). Creatine kinase-MB was elevated in 6 of 16 (38%) cords and in 8 of 15 (53%) neonates. Cardiac troponin I was elevated in 11% and 17% of samples; myoglobin in 4% and 17%; and high-sensitivity C-reactive protein in 9% and 40%. Measures of myocardial injury were associated with longer hospitalization (r = 0.50, P = 0.04), non-Caucasian race (P = 0.012), lower birth weights (P = 0.014), positive maternal cervical cultures (r = 0.41, P = 0.046), and elevated high sensitivity C-reactive protein (r = 0.66, P = 0.005). In conclusion, clinically occult myocardial injury appears to occur in some healthy newborns, although whether it is pathologic or not remains to be determined

Double-blind, randomized trial of a calf lung surfactant extract administered at birth to very premature infants for prevention of respiratory distress syndrome.

Organic solvent extraction of surfactant obtained by lavage of calf lungs yields a highly surface-active material. A double blind, randomized clinical trial to determine the effect of this material on respiratory distress syndrome in premature infants was initiated in the Neonatal Intensive Care Unit at the University of Rochester in December 1983. Infants 25 to 29 weeks gestational age were eligible for entry into the trial. At the time of this interim analysis 32 patients had been randomly selected and entered into the trial, 16 surfactant-treated patients and 16 in a control group who received only saline. At birth, intrapulmonary instillation of the calf lung surfactant extract dispersed in saline or saline alone occurred in the delivery room immediately after intubation and prior to ventilation; infants were then ventilated and treated as usual. At 6, 12, 24, 48, and 72 hours after birth, the severity of respiratory distress was categorized as either minimal, intermediate, or severe based on oxygen and mean airway pressure requirements. Differences observed at six hours after birth were of marginal significance, but at 12 and 24 hours the surfactant-treated group had significantly (P less than .01) less severe respiratory distress compared with the control group. Differences between treated and control infants were not statistically significant at 48 and 72 hours after birth. In four surfactant-treated infants the severity of respiratory distress worsened between 24 and 48 hours after birth, suggesting that one dose of surfactant at birth may not be sufficient for some infants

Salmonella Osteomyelitis of the Hand in an Infant with Sickle Cell Disease

Summary: Salmonella osteomyelitis involving the hand is a rare, but potentially morbid, complication of sickle cell disease in children. This entity can be difficult to distinguish from the more frequent presentation of dactylitis, but accurate diagnosis is critical to direct proper treatment. We report on a 15-month-old patient with sickle cell disease who ultimately developed osteomyelitis of 1 hand after an acute vasoocclusive episode caused 4 extremity dactylitis. The case description illustrates the diagnostic and treatment challenges